A novel method for measuring the charging kinetics of dielectrics under electron irradiation in SEM.

A novel method is proposed to measure the charging potential of dielectric targets under medium energy electron irradiation in a scanning electron microscope. The method is based on the measurement of backscattered electron signals by standard semiconductor or scintillation detectors. The signal is pre-calibrated by grey scale levels on the SEM screen. The detector signal is made up with backscattered and secondary electrons which are accelerated in the electric field created above the dielectric surface under irradiation.

3D surface topography imaging in SEM with improved backscattered electron detector: Arrangement and reconstruction algorithm.

We propose a new SFS (shape from shading) technique for improved 3D surface reconstruction and imaging of relatively smooth surface topography using the scanning electron microscope (SEM). The new arrangement of backscattered electrons detector plates allows decreasing the initial energy of the electron probe, which makes this SEM technique to be suitable for usage on radiation-sensitive samples like biological tissues. Experiments show high effectiveness of the method, which improves both the gradient sensitivity of the signal and the signal to noise ratio.

Backscattered electron detector for 3D microstructure visualization in scanning electron microscopy.

A new configuration of semiconductor detectors for backscattered electrons for a scanning electron microscope (SEM) is presented. The result of the optimization was the possibility to extract the information about the spatial relief (3D topology) of the sample and its subsurface structure (3D tomography) in the simplest way. The detector consists of 8 sensors-semiconductor plates, positioned in a certain way. The proposed method was tested on real structures having a surface micro relief or a subsurface volume structure. Experiments and simple calculations show increased effectiveness and a high signal-noise ratio in the proposed method. This is important, particularly for studying the radiation-sensitive biomedical tissue in SEM.

Electron-acoustic and surface electron beam induced voltage signal formation in scanning electron microscopy analysis of semiconducting samples.

The conditions for the detection of electron-acoustic (EA) and surface electron beam induced voltage (SEBIV) signals using a common sample mount and bottomside detection scheme are hereby discussed. It is shown that while the intrinsic properties of the sample under electron-beam irradiation would chiefly determine the presence of these contrast mechanisms, the manner in which the sample is mechanically and electrically configured in relation to the signal detection is crucial in determining the actual signal coupling mechanisms at work and hence the assumptions by which a robust and consistent interpretation of experimental results can be made. EA signals are detectable only if electrical coupling between the sample and the detector is defeated, a necessary pre-requisite as the signal magnitude of carrier-generated SEBIV coupling is 2-3 orders larger in most cases. With regards to SEBIV detection, bottomside SEBIV detection may be preferable to topside detection owing to minimization of topographic signal contribution, higher signal coupling efficiency and a less complex sample-detector mounting procedure.

Light collection efficiency and light transport in backscattered electron scintillator detectors in scanning electron microscopy.

Experimentally, scintillator detectors used in scanning electron microscopy (SEM) to record backscattered electrons (BSE) show a noticeable difference in detection efficiency in different parts of their active zones due to light losses transport in the optical part of the detector. A model is proposed that calculates the local efficiency of the active parts of scintillator detectors of arbitrary shapes. The results of these calculations for various designs are presented.

An anomalous contrast in scanning electron microscopy of insulators: the pseudo-mirror effect.

In a scanning electron microscope, electron-beam irradiation of insulators may induce a strong electric field due to the trapping of charges within the specimen interaction volume. On one hand, this field modifies the trajectories of the beam of electrons subsequently entering the specimen, resulting in reduced penetration depth into the bulk specimen. On the other hand, it leads to the acceleration in the vacuum of the emitted secondary electrons (SE) and also to a strong distortion of their angular distribution. Among others, the consequences concern an anomalous contrast in the SE image. This contrast is due to the so-called pseudo-mirror effect. The aim of this work is first to report the observation of this anomalous contrast, then to give an explanation of this effect, and finally to discuss the factors affecting it. Practical consequences such as contrast interpretations will be highlighted.